The degeneration of the intervertebral disc, characterized by chronic pain, restricted range of motion, and progressive deterioration of functional spinal units, represents a serious surgical condition. For the treatment the total or partial arthroplasty is often suggested. Currently, 3D printing is frequently utilized in the development of disc prostheses, owing to its high precision and capacity to create patient-specific implants. Integrated with the replication of the intact biphasic structure, this approach facilitates the preservation of the natural biomechanical response to physiological loads. For the artificial annulus fibrosus, gyroid-based structures fabricated using biocompatible materials show significant promise due to their unique mechanical properties. Hydrogels can serve as candidates for the nucleus pulposus replacement, due to their structural similarity and viscoelastic behavior. This work proposes design methodologies for an annulus fibrosus with gyroid structure, manufactured via extrusion-based 3D printing. Furthermore, a fabrication technique for hydrogels exhibiting controlled swelling and a tailored elastic modulus to mimic the nucleus pulposus was implemented. Mechanical testing was conducted to evaluate the elastic-hysteretic properties of the hybrid implant prototypes under physiological loading conditions. The results demonstrate a close correspondence between these properties and those of the intact disc.

The growth of cell culture in porous scaffolds depends on the pore architecture and the distribution of growth factors, including their desorption from the porous matrix. Mathematical modeling allows for the quantitative assessment of the influence of channel geometry and boundary conditions on the morphological and mechanical characteris-tics of a cell culture. This paper presents a mathematical model of cell tissue growth in scaffold pores of various geometries, taking into account the desorption of growth fac-tors from the walls of the porous matrix. Three channel configurations are considered: straight, sinusoidal, and gradient-periodic. The model is based on a vertex model, which enables tracking of the morphometric, mechanical, and energy characteristics of each cell over time. A comparative analysis of key indicators was conducted: tissue growth rates, average cell shape factor, normalized average cell area, potential energy, and the distribution of maximum shear stresses. It is shown that the channel shape significantly affects the extreme values of mechanical characteristics despite similar average values. Sinusoidal channel geometry leads to increased peak energy values and a more elon-gated cell morphology. Straight channels provide higher growth rates in the early stag-es. The gradient-periodic channel shape demonstrates intermediate values in terms of growth rates and key indicators. The obtained conclusions can serve as a basis for op-timizing the architecture of porous carriers in tissue engineering to control mechanical load and cell morphology. The developed mathematical model allows for predicting the morphological and mechanical responses of a cell culture to changes in pore geometry, which expands the possibilities for the targeted design of scaffolds.

Additive technologies have made it possible to create medical devices with inhomogeneous structure. The structures of such products, called metamaterials, allow not only to reduce the weight of the product, but also to control the effective physical and mechanical properties by varying the geometry of their microarchitecture. Controlling physical-mechanical properties helps prevent post-operative complications associated with implantation. This study focuses on determining the stiffness and strength properties of different types of the lattice metamaterials, which are subsequently used to develop a numerical model and design endoprostheses, as well as to investigate antibiotic elution from bone cement. The work presents an experimental testing of three metamaterial types with two variations of cross-sectional angle, both with and without embedded cement. The cross-sectional angles of the specimens were selected based on the results of numerical simulations. The studied specimens were fabricated using laser stereolithography on a photopolymer printer, followed by post-polymerization. Stiffness properties were determined through using in situ four-point bending tests. As a result, the stiffness and maximum load values were obtained. These values were normalized to those of solid specimens. The specimens with embedded cement were at least 28 % stiffer than those without cement. A comparison of numerical and in situ experiments revealed qualitative agreement in the results for the first and third types of specimens when the cross-section rotation was varied. However, the maximum load observed of the in situ experiments for the strongest specimens, according to the numerical model, showed little difference compared to the maximum loads of other specimens types. The authors attribute this result to the dependence of changes in physical and mechanical properties on geometry during polymerization.

Modern methods of human posture and movement assessment used in medical practice for diagnosing and monitoring the condition of patients with musculoskeletal disorders are discussed in the article. The advantages and disadvantages of traditional methods, such as goniometry and body topography, as well as modern technologies, including 3D video analysis systems, are described. The authors propose a new ap-proach based on the use of digital video cameras to create standardized video protocols for patient screening. This methodology provides accessibility, objectivity, and the pos-sibility of application in the routine practice of doctors from various specialties, such as neurology, orthopedics, rehabilitation, and sports medicine. The aim of the research is to develop a technology for assessing static coordination and detecting body asymmetry in patients. The developed software and hardware system provides automated pro-cessing of video recordings to analyze human posture symmetry. This process begins with marking the first frame and concludes with the calculation of numerical characteris-tics based on segmentation and object tracking. The program utilizes a pre-trained neural model to segment images and identify control points such as the center of mass, key joints, and body lines. The program allows to save angles, area and deviations at each moment in time. The processing results are then converted into numerical tables and visualized as plots. The software is designed to generate video protocols, facilitating dynamic assessment of patients in ambulatory care settings. Its application revealed pos-itive results: patients were divided into three significant groups, which correlates with common musculoskeletal syndromes. Specifically, the identified groups correspond to comorbidities in the craniocervical-shoulder and lumbar-femoral regions, as well as a combination of temporomandibular joint dysfunction with psychological affective disor-ders. These findings highlight the potential of digital visual assessment for accelerating patient diagnosis and identifying muscle imbalances caused by modern sedentary life-styles.

Osteoarthritis of the knee joint is a common pathology. Damage to the posterior root of the medial meniscus of the knee joint can lead to the progression of this pathology. In turn, the damage often occurs due to overloading of the medial compartment of the joint, due to varus deformity. There is a technique called proximal fibular osteotomy (PFO), which involves resection of a section of the fibula proximally. Numerous studies have demonstrated its clinical efficacy in the treatment of knee joint pathologies involving the medial compartment. However, the mechanism and effectiveness of this procedure are not understood. In this work, a 3D-model of the lower limb was constructed, taking into account the ligamentous apparatus and trabecular elements of the femoral and tibial apexes. The influence of human weight, small varus deformity (~ 2 degrees) and proximal fibula osteotomy on the stress-strain state of the menisci of the knee joint and articular surfaces of the knee joint was investigated using the finite element method. It is shown that the zone of maximum stresses is located in the area of the posterior horn of the medial meniscus, with increasing load there are zones of increased stresses in the central part of the medial meniscus body, as well as in the area of the anterior horn of the lateral meniscus. It was found that PFO reduces stress values and decreases the areas of high stress on the medial meniscus, which may be evidence of the effectiveness of this operation.

Physical phantoms are reference objects designed for standardizing scanning pro-tocols, calibrating tomographs, quality control of images, and testing magnetic reso-nance imaging MRI methods without involving patients. Currently, in addition to qualita-tive visualization, quantitative methods of MRI are being developed. To ensure uniformity in the interpretation of results and to develop new scanning methods and pulse se-quences, it is necessary to use specialized test objects–phantoms that mimic physiologi-cally significant relaxation times. Anthropomorphic physical phantoms serve as reliable tools for the development and investigation of new MRI methods. The aim of this review is to analyze the literature on existing anthropomorphic brain phantoms while summariz-ing researchers' experiences in their fabrication. The review analyzed literature from two databases: Google Scholar and PubMed. Only anthropomorphic MRI phantoms made from materials with relaxation times close to those of brain tissues, which typically in-clude several components (T1 and T2 modifiers), were included in the review. A brief comparative characterization of the phantoms described in the review is summarized in a table, indicating the mimicked tissues, relaxation times, materials used for fabrication, and areas of application. The issue of creating brain phantoms for children and fetuses, whose relaxation characteristics and anatomy differ from those of adults, remains unre-solved. Information about the possibilities and methods for manufacturing anthropo-morphic phantoms for MRI will assist specialists in medical imaging, biochemistry, and biomechanics in addressing the relevant multidisciplinary practical task of modeling and utilizing them in preclinical research.

One of the world trends of Industry 4.0 is the introduction of exoskeletal technologies into production processes. Manufacturers of industrial exoskeletons designed to reduce the negative impact of the work process on the human locomotive apparatus provide for the redistribution of the external load on the human body by means of various technical solutions. However, there is currently no uniform methodology for assessing the operational safety of exoskeletons. A significant biomechanical factor contributing to the safety of industrial exoskeletons as promising means of personal protection of the locomotor apparatus, is possibility to work without significant restrictions on the volume of movements. In this connection, the development of a methodology for objective quantification of the influence of structural and mass dimensions of industrial exoskeletons on the biomechanics of human movements is a topical task. This article presents the results of the measurements of the amplitude of movements in the large joints and joints of the spine, when performing the tests for flexion-extension, adduction-abduction and lateroflexion. The testing of volunteers was carried out on the clinical base of Research Institute of Labor Medicine. The tests were performed both without the use of industrial exoskeletons (Group I) and with their application (Group II). The influence on the biomechanical parameters of volunteer movements by the structural characteristics of the industrial exoskeleton “Exochair” and two different models of the industrial exoskeleton «Exoatlant» was investigated. Parameters of movements of segments of the human body were measured with the help of inertial measuring sensors of the software and hardware complex «Biomechanika Trust-M». Quantitative indicators have been identified which show the limitations of movements caused by the operation of different models of industrial exoskeletons. Thus, the use of the exoskeleton “Exochair” in deep seating limits the flexion in the hip joint by 67.1%, in the knee joint by 56.1%, in the lumbar thoracic spine by 61.9%, and practically does not affect the flexion in the shoulder joint. The first model of the exoskeleton “Exoatlant” limits the amplitude of movements in the hip joint by 41.2% at flexion and by 74.5% at extension. At the same time, the second model limits the abduction of the shoulder joint by 20.5%, and in the lumbar thoracic spine limits forward flexion by 17.3%, rearward extension by 50.6%, bending to the right by 46.4%, and bending to the left by 40.3%.

The stress-strain state of the human eye, which cornea in its apexis is weakened after myopia surgical correction, is studied. The elastic system “corneasclera” is presented as two joint transversely isotropic spherical segments with nonuniform thickness, different radii of curvature and biomechanical properties. The cornea is modeled as multilayer shell. The simulated eye shell is filled with an incompressible fluid. Mathematical models of three different laser vision correction surgeries: small incision lenticule extraction (SMILE), laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK), are developed in the engineering simulation software ANSYS Inc. The diameter and thickness of the lenticular in SMILE, the diameter of the ablation zone and the maximum thickness (depth) of the corneal ablation in LASIK and PRK define optical surgery areas and are considered as comparable parameters. Finite element simulation shows that after LASIK vision correction the apex of the cornea has a greater displacement and the stress increase greater in the stroma than after SMILE and PRK. The influence of the multilayer structure of the cornea and elastic characteristics of the sclera on the biomechanics of the eye as a result of vision correction is shown.

The study of the stress-strain state of the biomechanical system "pelvis - customized implant" by the finite element method is widely used in the treatment of pelvic injuries in orthopedics. However, the effect of the complex loading conditions that a person encounters on a daily basis on the behavior of the hip joint is not well understood. This work is devoted to the study of the stress-strain state of the biomechanical system formed by an endoprosthesis of the hip joint and the bones of the pelvic region of a person while walking. As part of solving the problem, the features of the creation of finite element models of the pelvic bones and an individual endoprosthesis were considered on the basis of the initial geometric models obtained from the Federal State Budgetary Institution "National Medical Research Center of Traumatology and Orthopedics named after R.R. Vreden" (St. Petersburg) and performed a series of strength calculations for the walking pattern. The implant model replaced the primary installed prosthesis, which was lost due to the development of instability of the acetabular component. Analysis showed that the screws and the endoprosthesis have a sufficient margin of safety, while in the bone tissue one can expect local micro-destruction in the zone of its contacts with the screws. During the operation, it is worth focusing on the bonding of the implant to the bone tissue in order to avoid unwanted destruction of the cortical layer around the holes. Based on the analysis results, a recommendation can be made to exclude screws numbered eight and nine, since neither the screws nor the holes for them are subjected to heavy loads.

Functional movements of the lower jaw occur during chewing, swallowing, and talking. These movements are considered with in three planes within certain limits. Many works of domestic and foreign researchers are devoted to the location of teeth in the interdigital space. The main theories of articulation were proposed by W.G. Bonvil (1858), F. Spee (1896), D. Monson (1917), and others. The dentoalveolar system is a closed kinematic system in which all the elements are interconnected and represent concentric circles and spheres with a single functional center. In this article, the location of the teeth in the space of the occlusal sphere on the tomograms of the patients ' heads in the lateral and axial projections is considered. It was found that in patients with brachygnatic structure of the gnatic part of the face, characterized by wide and short dental arches, the teeth in the large occlusal space were located at a lower angle to the center of the circle than in patients with mesognatic structure. In patients with dolichognathic structure, which is characterized by narrow and long dental arches, in a small occlusal space, the teeth were located at a greater angle to the center of the circle, compared to the other two types of structure. The location of the teeth at an angle characteristic of each of the types of structure of the gnatic face shape caused the severity of the compensatory sagittal and transversal curves. This circumstance determines the optimal functional dynamics of the lower jaw in the space of the occlusal sphere of the maxillofacial part of the skull. This eliminates acute and chronic occlusal trauma, normalizes the function of the masticatory muscles and joints.